title: The Arabidopsis LRR-RLK, PXC1, is a regulator of secondary wall formation correlated with the TDIF-PXY/TDR-WOX4 signaling pathway.
abstract: BACKGROUND
  Although a number of leucine-rich repeat receptor-like kinase-encoding genes (LRR-RLKs) have been identified in plants, a functional role has been determined for only a few. Recent studies have demonstrated that an LRR-RLK, PXY/TDR, is important for the process of secondary vascular development. Other studies have indicated that PXY/TDR is unlikely to be the sole LRR-RLK involved in this complex process.
  
  
  RESULTS
  In this study, in silico analyses led to the identification of three Arabidopsis LRR-RLK genes (PXY-correlated; PXC1, 2, 3) with transcript accumulation profiles that correlated strongly with several key regulators of vascular development, including PXY/TDR, HB-8, REV, and CLE41. Expression profiling using qPCR and promoter:reporter lines indicated that all three PXC genes are associated with the vasculature. One in particular, PXC1 (At2g36570), had a strong correlation with PXY/TDR. Shifting pxc1 mutants from long-days to short-days showed that loss of the gene led to a dramatic reduction in secondary wall formation in xylem fibers. Transcript analysis of mutants for a variety of secondary cell wall-associated genes, including PXY/TDR indicated that the pathways mediated by PXC1 connect with those mediated by the TDIF-PXY/TDR-WOX4 system.
  
  
  CONCLUSIONS
  The data indicate that the LRR-RLK, PXC1 is involved in secondary cell wall formation in xylem fibers. Whereas further study is needed to identify the ligands and mode of action of the PXC1 protein, it is clear from this work that similarly to the shoot apical meristem (SAM), secondary vascular development requires contributions from a number of LRR-RLKs.
authors.affiliation: School of Environmental Science and Engineering, Tianjin University, 300072 Tianjin, China.
authors.forename: Jiehua
authors.initials: J
authors.lastname: Wang
authors.forename: Melis
authors.initials: M
authors.lastname: Kucukoglu
authors.forename: Linbin
authors.initials: L
authors.lastname: Zhang
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Daniel
authors.initials: D
authors.lastname: Decker
authors.forename: Ove
authors.initials: O
authors.lastname: Nilsson
authors.forename: Brian
authors.initials: B
authors.lastname: Jones
authors.forename: Göran
authors.initials: G
authors.lastname: Sandberg
authors.forename: Bo
authors.initials: B
authors.lastname: Zheng
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D052584:Xylem / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D009842:Oligopeptides; C581875:WOX4 protein, Arabidopsis; C532424:tracheary element differentiation inhibitory factor, Arabidopsis; D011494:Protein Kinases; D020794:Receptor Protein-Tyrosine Kinases; C543878:At2g36570 protein, Arabidopsis; C524131:PXY protein, Arabidopsis